Shake at 30 mph

[dhoey1212]

Good afternoon guys and gals,
I am trying to track down an issue on my girlfriends 2010 Sahara Unlimited 4 Door. There is this shake or wobble at about 25-35 mph under acceleration. Take the foot of the gas and it goes away, accelerate through it hard and it goes away. Tires have been rotated and checked, got an alight meant recent and the issue persists. Thinking either something with the trans, maybe u-joints on the driveline, or possibly something with the steering rack although it happens regardless of wheel position. Anyone have a similar problem or find a fix for this?

 

[tJKrider]

You can try a different trans gear at the same vehicle speed to rule that out, assuming the issue follows vehicle speed...

Could be driveshaft balance or a u-joint. Your comment about lifting off the gas, however, makes me lean towards either a driveshaft u-joint or pinion bearing. Those tend to respond to the loading/un-loading of the driveline.

I've also had rear axle bearings (on a different vehicle) going bad that would hum and vibrate at a certain speed. Higher or lower and they were silent. That was independent of accel or decel, though, just hitting the right speed...

 

[dhoey1212]

Update, replaced the rear axle seals and changed the diff fluid and all is well no more shake

 

[BLACKJKU]

Update, replaced the rear axle seals and changed the diff fluid and all is well no more shake

Did you happen to also swap the tires around? R&R seals and diff fluid change wouldn't have stopped a shake.

 

[dhoey1212]

Did you happen to also swap the tires around? R&R seals and diff fluid change wouldn't have stopped a shake.

Fluid in the rear diff was significantly low from leaking, wondering if that could’ve been the issues. Been driving for over a year and shake has not returned. I also did loosen and add loctite to the drive shaft bolts and all is good

 

[BLACKJKU]

Fluid in the rear diff was significantly low from leaking, wondering if that could’ve been the issues. Been driving for over a year and shake has not returned. I also did loosen and add loctite to the drive shaft bolts and all is good

The only thing that would happen from low fluid is the bearings inside the center section going bad from low/no oil. Filling it up to the proper level wouldn't have saved any bad bearings.